Frost can cause extensive damage to agricultural products. Most vulnerable are fruit trees that blossom in early spring. Fruit that survives a frost can still be damaged or destroyed if the subsequent thaw is too rapid. Freeze damage problems cost millions of dollars each year, both in terms of lost profits to the farmer and in higher prices for the consumer.
To combat the destruction of frost, one of the early preventative measures was to use lighted smudge pots in the orchard. The smudge pot operates by burning oil in a container. The result is two-fold. First, heat is produced to offset the cold front and raise the temperature in the orchard to above dangerous levels. Second, smoke provides a blanket of insulation to retain the heat in the orchard. This blanket of smoke or mantle is referred to as "smudge". Modern smudge pots burn cleaner than earlier models but are still an environmental concern.
Another conventional technique is to spray water over the orchard or crops using an overhead irrigation system. The effectiveness of the air to trap and hold the earth's radiant heat increases with the dew point. Also, the condensation of the water vapor on the fruit releases energy (i.e., the heat of fusion), thus raising the temperature of the fruit. This method is seldom used, however, because there is a significant risk of damage to the trees from branches breaking under the load of frozen water. This approach to orchard freeze protection also is costly to install and operate because a water heater or boiler and large amounts of distribution piping are required.
A third technique used to combat the orchard frost problem is the wind machine. Propellers mounted on a ten to fifteen meter tower mix the air forcing cold air up and warm air down into the orchard. Helicopters have been employed for similar effects where the orchard is not equipped with wind machines.
This invention provides a new technique for preventing the formation of frost on fruit trees and other agricultural crops.